Centre of Navigation
The mathematical point, referenced to the associated with the DGNSS navigation solution. This point would typically of the GNSS antenna, but could also be an offset or translated point (e.g. might be translated vertically to the level of the wheels of a large aircraft).
Certification
A process by which an authorised body, acting within a legislative framework gives formal recognition that a product, process or service conforms to applicable safety regulatory requirements.
Chain
A set of objects which belongs to same target and associated to each other via aircraft identifier field in MADREC.
Chaining
1- General: A process of linking together radar target reports (plots and tracks) and other
information relating to one particular object.

2- SASS-C: All plots relating to the same target object are associated (chained) using the Object Correlate (OC). The chaining process allocates the same aircraft identity number (ACID) to each plot which relates to one target object. Any plots which cannot be correlated to a target object are classified as unchained and are allocated a negative aircraft identification.
Change of Control Frequency Reminder
A reminder that is provided a time parameter before or after the calculated time of change of control frequency based on the Letter of Agreement with the receiving ATC unit or Standard Operating procedures for intra-ATC unit changes. The reminder will include identification of the flight, identification of the next ATC sector, new R/T frequency. The reminder will not be issued if the control frequency has already changed. The reminder is directed at the Sector Controller currently in control of the associated flight.
Change-Over Point
The point at which an aircraft navigating on an ATS route segment defined by reference to very high frequency omni-directional radio ranges is expected to transfer its primary navigational reference from the facility behind the aircraft to the next facility ahead of the aircraft.
Channel
The path in a GPS receiver that processes the signal from a single satellite.
Channel Rate
The rate at which bits are transmitted over the RF channel. These bits include those bits used for framing and error correction, as well as the information bits. For burst transmission, the channel rate refers to the instantaneous burst rate over the period of the burst.
Channel Rate Accuracy
This a relative accuracy of the clock to which the transmitted channel bit is synchronised. For example, at a channel rate of 1.2 kbits/s, maximum error of one part in 106 implies the maximum allowed error in the clock is ± 1.2 x 103 Hz.
Checking
One of the basic functions of ATC which consists of selecting information from a new situation in order to update the actual Mental Picture (MP).
Checklist
A NOTAM published regularly in a NOTAM series containing a list of valid NOTAM numbers grouped by year promulgated in this series.